| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 45°F | 69°F | 56°F | 1.9" |
| February | 47°F | 69°F | 57°F | 2.2" |
| March | 50°F | 70°F | 59°F | 1.0" |
| April | 53°F | 72°F | 61°F | 0.7" |
| May | 57°F | 72°F | 63°F | 0.4" |
| June | 61°F | 76°F | 66°F | 0.0" |
| July | 65°F | 80°F | 71°F | 0.2" |
| August | 66°F | 82°F | 72°F | 0.0" |
| September | 64°F | 83°F | 72°F | 0.2" |
| October | 58°F | 80°F | 68°F | 0.5" |
| November | 51°F | 74°F | 62°F | 0.9" |
| December | 46°F | 68°F | 56°F | 2.5" |
| Index | Rancho San Diego | California | National |
| Air quality index | 64 | 55 | 42 |
| Pollution index | 162,740 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 87 |
| Days with moderate air quality | 253 |
| Days w/ poor A.Q. for sensitive groups | 23 |
| Days with unhealthy air quality | 2 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.003% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| La Mesa, CA | 60,208 | 64 | 28.0% |
| Jamul, CA | 5,776 | 64 | 28.0% |
| San Diego, CA | 1,414,545 | 64 | 28.0% |
| Bostonia, CA | 17,532 | 64 | 28.0% |
| Eucalyptus Hills, CA | 6,448 | 64 | 28.0% |
| Rancho San Diego, CA | 21,476 | 64 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Ballenger Creek, MD | 21,484 | 40 | 20.0% |
| Varennes, QC | 21,490 | n/a | |
| Ramona, CA | 21,493 | 64 | 28.0% |
| South Holland, IL | 21,451 | 55 | 10.0% |
| Biddeford, ME | 21,502 | 40 | 20.0% |
| Rancho San Diego, CA | 21,476 | 64 | 28.0% |
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